Hold the Power button down for more than one second. However, first:
Check to make sure that the data lamp isn't flashing. If it is, the printer is receiving a job to print and turning off the printer during printing could damage the printer.
Check to make sure that the Message lamp isn't flashing. If it is, attend to the problem before turning off the printer.
How do I turn the printer off?
Hold the Power button down for more than one second. However, first: